While techniques, practices and resources in tunnelling are continually improving, risk will never be eliminated and the ways to manage it must be updated and maintained alongside them. Tunnelling is one of the most complex and challenging engineering tasks, meaning that the risk is high and the management of risk on any project is imperative.
The fires which broke out at High Speed 2’s Chiltern Tunnel and Transport for London’s Silvertown Tunnel in 2022 go to show that even the best prepared and best funded projects face risks. At the same time, extreme rainfall events have made tunnelling losses to water related issues – such as ingress and flooding – more common.
The third edition of the Code of Practice for Risk Management of Tunnel Works was published in March. It acknowledges that the ways tunnels are designed and the environments into which they are being introduced have changed. The new code updates its risk management guidance to align it with the demands of modern global market.
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History of the code
The idea for a tunnelling code of practice followed a number of under-construction tunnel failures in the UK, most notably the Heathrow Express tunnel collapse of October 1994. The frequency of insurance claims from tunnel projects had led to a loss of confidence from insurers.